FDH: A Novel Determinant of Tumor Suppression

FDH：肿瘤抑制的新决定因素

基本信息

批准号：
7558315
负责人：
SERGEY A KRUPENKO
金额：
$ 24.61万
依托单位：
MEDICAL UNIVERSITY OF SOUTH CAROLINA
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-03-01 至 2010-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7558315
关键词：
A549 Address Anabolism Apoptosis Apoptotic Bladder Bladder Neoplasm Cancer cell line Cell Death Cell Survival Characteristics Clinical Research CpG Cluster CpG Islands DNA Damage DNA Methyltransferase Inhibitor DNA Repair Deoxycytidine Down-Regulation Enzymes Epithelial Folate Formyltetrahydrofolates Gene Silencing Genes Goals Hypermethylation Investigation Link Malignant - descriptor Malignant Neoplasms Mediating Metabolic Metabolic Pathway Methylation Molecular Neoplastic Cell Transformation Non-Malignant Normal Cell Oxidoreductase Prevention Primary Cell Cultures Process Purines RNA biosynthesis Regulation Resistance Role Site TP53 gene Testing Tetrahydrofolates Tissues Toxic effect Transfection Tumor Suppression Tumor Suppressor Genes Tumor Suppressor Proteins Tumor Tissue cancer cell cell growth cytotoxic cytotoxicity density insight novel promoter purine research study tumor

项目摘要

DESCRIPTION (provided by applicant): The overall goal of this proposal is to characterize the novel tumor suppressor activity of a key metabolic enzyme and to determine the mechanism(s) of its selective toxicity to malignant vs. non-malignant cells. FDH (10-formyltetrahydrofolate dehydrogenase) irreversibly converts 10-formyltetrahydrofolate, an essential substrate for de novo purine biosynthesis, to tetrahydrofolate. Through depletion of this substrate, FDH can restrict purine biosynthesis. In turn, this interferes with important downstream intracellular processes, including DNA/RNA biosynthesis and DNA repair. Because of this critical metabolic function, down-regulation of FDH in cancer cells was predicted to be prosurvival, while artificial elevation through stable transfection, would be toxic. We have recently made the important observation that FDH is strongly and ubiquitously down-regulated in tumor tissues and cancer cell lines and that FDH promoter hypermethylation is likely involved in this down-regulation. We have further demonstrated that moderate FDH expression in FDH-deficient cancer cells induces apoptotic cell death. Furthermore, evidence was recently obtained that p53 is required to mediate FDH-induced cytotoxicity. In contrast, non-cancer cells were insensitive to FDH elevation. Therefore, it is proposed that cancer cells silence the FDH gene in order to escape cytotoxicity. Our central hypothesis is that FDH down-regulation through promoter hypermethylation is one of the important means by which malignancies gain pro-survival advantage over normal cells. The Specific Aims that will be used to address this hypothesis are: (1) Determine the molecular mechanisms of FDH-induced apoptosis in transfected cancer cells, (2) Elucidate the mechanism(s) that protects non-malignant cells from FDH-induced apoptosis, and (3) Determine the role of promoter hypermethylation in down-regulation of FDH in cancer cells. Stable clones of malignant cells that inducibly express FDH, resistant cancer cell clones that have acquired the ability to constitutively express FDH, and FDH-insensitive non-malignant cells, will be used to pursue the goals of this project. It is proposed that investigation of the critical role of FDH in cancer cell survival will provide important insight into the malignant process itself and link disregulation of important metabolic pathways to cell death.

描述（由申请人提供）：该提案的总体目标是表征关键代谢酶的新型肿瘤抑制活性，并确定其对恶性和非恶性细胞的选择性毒性的机制。 FDH（10型甲基四氢叶酸脱氢酶）不可逆转地转化10型甲基四氢叶酸，这是从头嘌呤生物合成的必不可少的底物，为四氢叶酸盐。通过耗尽该底物，FDH可以限制嘌呤的生物合成。反过来，这会干扰重要的下游细胞内过程，包括DNA/RNA生物合成和DNA修复。由于这种关键的代谢功能，预计癌细胞中FDH的下调为prosurvival，而通过稳定转染的人工升高将是有毒的。我们最近对肿瘤组织和癌细胞系中FDH的强烈和普遍下调的重要观察结果进行了重要观察，并且FDH启动子高甲基化可能参与了这种下调。我们进一步证明，FDH缺陷癌细胞中的中等FDH表达会诱导凋亡细胞死亡。此外，最近有证据表明，需要p53介导FDH诱导的细胞毒性。相反，非癌细胞对FDH升高不敏感。因此，有人提出癌细胞使FDH基因沉默以逃避细胞毒性。我们的中心假设是，通过启动子高甲基化的FDH下调是恶性肿瘤比正常细胞促生存优势的重要手段之一。将用于解决这一假设的具体目的是：（1）确定转染的癌细胞中FDH诱导的细胞凋亡的分子机制，（2）阐明了保护非触发细胞免受FDH诱导的细胞凋亡的机制，（3）确定启动子高甲基化在癌细胞中FDH下调中的作用。稳定的恶性细胞克隆，可诱导表达FDH，具有组成性表达FDH和FDH不敏感的非敏感细胞能力的抗性癌细胞克隆将用于追求该项目的目标。有人提出，对FDH在癌细胞存活中的关键作用的研究将提供对恶性过程本身的重要见解，并将对重要代谢途径的疏离与细胞死亡联系起来。